At first blush, it appears to be working - if you click the first thumbnail, the expander for the video shows the prev/next arrows, as well as the on-image navigation. But now close that video, and try launching the gallery again, from any of the thumbnails. The prev/next arrows are no longer visible, nor are the on-image navigation arrows.

If you refresh the page (CTRL-F5), then launch the gallery, all is well again.